Abstract

Few published studies of Cenozoic regional uplift and erosion exist for the Eastern (Russian) part of the Barents Sea. The study presented here used several methods to estimate uplift/erosion values for the region, the principal technique being the use of generalised porosity-depth trends. Geophysical well logging data for 33 Russian offshore wells were compiled and processed. The joint interpretation of sonic, gamma-ray, resistivity and spontaneous potential logs was used to calculate porosity and shale fraction for siliciclastic rocks. Comparison of smoothed exponential porosity-depth curves from different wells revealed the rate of compaction for different kinds of sediments and different level of erosion as reference. Vitrinite reflectance and sonic logs were used to provide independent evaluation of the uplift and erosion for calibration. Differential exhumation had occurred throughout the study area. The wells in the centre of the South Barents Basin experienced the least exhumation (400-500 m); the magnitude increases northward up to 2000 m on Franz Josef Land. Uplift/erosion also increases eastward (the total thickness of eroded rocks for the Admiralteyskaya-1 well near Novaya Zemlya is about 1500 m). Preliminary estimates of exhumation on the Pechora Sea shelf suggest about 1000-1300 m (using both porosity trends and vitrinite Ro data). The improved estimation of burial and uplift history was used to constrain 1D petroleum systems modelling.